Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2

Abstract

Thermoelectric properties of the layered cobalt oxide system LixCoO2 were investigated in a wide range of Li composition, 0.98 >= x >= 0.35. Single-phase bulk samples of LixCoO2 were successfully obtained through electrochemical deintercalation of Li from the pristine LiCoO2 phase. While LixCoO2 with x >= 0.94 is semiconductive, the highly Li-deficient phase (0.75 >= x >= 0.35) exhibits metallic conductivity. The magnitude of Seebeck coefficient at 293 K (S293K) significantly depends on the Li content (x). The S293K value is as large as +70 ~ +100 uV/K for x >= 0.94, and it rapidly decreases from +90 uV/K to +10 uV/K as x is lowered within a Li composition range of 0.75 >= x >= 0.50. This behavior is in sharp contrast to the results of x <= 0.40 for which the S293K value is small and independent of x (+10 uV/K), indicating that a discontinuous change in the thermoelectric characteristics takes place at x = 0.40 ~ 0.50. The unusually large Seebeck coefficient and metallic conductivity are found to coexist in a narrow range of Li composition at about x = 0.75. The coexistence, which leads to an enhanced thermoelectric power factor, may be attributed to unusual electronic structure of the two-dimensional CoO2 block.

arXiv comment29 pages, 1 table, 8 figures

References in corpus (19)

• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Large enhancement of the thermopower in Na${}_x$CoO${}_2$ at high Na doping
• "Pudding mold" band drives large thermopower in Na${}_x$CoO${}_2$
• Patterning of sodium ions and the control of electrons in sodium cobaltate
• Unconventional magnetic transition and transport behavior in Na0.75CoO2
• Charge Disproportionation and Spin Ordering Tendencies in Na(x)CoO2
• Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0)
• Synthesis and properties of CoO2, the x = 0 end member of the LixCoO2 and NaxCoO2 systems
• Searching for Stable Na-ordered Phases in Single Crystal Samples of gamma-NaxCoO2
• Sodium vacancy ordering and the co-existence of localized spins and itinerant charges in NaxCoO2
• Disproportionation Transition at Critical Interaction Strength: Na${}_{1/2}$CoO${}_2$
• Magnetic and Electronic Properties of Li${}_x$CoO${}_2$ Single Crystals
• Discontinuous Lifshitz Transition Achieved by Band-Filling Control in NaxCoO2
• Precise Control of Band Filling in NaxCoO2
• Transport properties of the layered Rh oxide K_0.49RhO_2
• Measurement of electron correlations in LixCoO2 (x=0.0 - 0.35) using 59Co nuclear magnetic resonance and nuclear quadrupole resonance techniques
• Metal-nonmetal transition in LixCoO2 thin film and thermopower enhancement at high Li concentration
• Electrochemical synthesis and properties of CoO2, the x = 0 phase of the AxCoO2 systems (A = Li, Na)
• Chemical Differences between K and Na in Alkali Cobaltates

Cited by in corpus (6)

• From charge- and spin-ordering to superconductivity in the organic charge-transfer solids
• Colossal Thermoelectric Power Factor in K${}_{7/8}$RhO${}_2$
• A multi-technique approach to understanding delithiation damage in LiCoO2 thin films
• Novel electronic states realized by the interplay between Li diffusion and Co${}^{3+}$$/$Co${}^{4+}$ charge ordering in Li${}_{\mathrm{x}}$CoO${}_2$
• Is there a common theme behind the correlated-electron superconductivity in organic charge-transfer solids, cobaltates, spinels and fullerides?
• Similarities in electronic properties of organic charge-transfer solids and layered cobaltates